<?php
/**
 * Created by PhpStorm.
 * User: User
 * Date: 2017/9/20
 * Time: 9:04
 */

$num1=$_GET["num1"];
$num2=$_GET["num2"];
$op=$_GET["op"];

?>
<html>
<body>
<form action="cal.php" method="get">
<input type="text" name="num1" value="<?php echo $num1?>"/>
<select name="op">
    <option value="+"<?php echo $op=='+'?' selected':''?>>+</option>
    <option value="-"<?php echo $op=='-'?' selected':''?>>-</option>
    <option value="*"<?php echo $op=='*'?' selected':''?>>*</option>
    <option value="%" <?php echo $op=='%'?' selected':''?>>%</option>
</select>
<input type="text" name="num2" value="<?php echo $num2?>"/>
=
<input type="text" name="result">
<button type="submit">计算</button>
</form>
</body>

</html>
